1. Field of the Invention
This invention relates to a method of and an apparatus for shaping a film cartridge for accommodating therein a roll film, and more particularly to a method of bending a shell plate into a hollow cylinder, capping the hollow cylinder and clinching the assembly thus obtained, and to an apparatus for carrying out the method.
2. Description of the Prior Art
There have been put into practice various methods of and apparatuses for bending a shell plate into a hollow cylinder, mounting caps on the upper and lower ends of the hollow cylinder (capping), and clinching the assembly thus obtained in shaping of a film cartridge. For example, in Japanese Unexamined Patent Publication No. 59(1984)-143841, there is disclosed an improvement on such an apparatus and a method.
Conventionally, there has been encountered a problem in shaping of the film cartridge that when a mandrel having a perfectly circular cross section is used for bending the shell plate, the cross section of the obtained shell does not become perfectly circular due to the spring back effect of the shell plate. Accordingly, a mandrel having an ellipsoidal cross section has been generally used. However, the ellipsoidal mandrel is disadvantageous in that since the cap, which is perfectly circular in shape, cannot be mounted on the shell plate as the shell plate is bent around the ellipsoidal mandrel, the shaped shell plate must be removed from the mandrel and the removed shell plate having an .OMEGA.-shaped cross section must be conveyed to and positioned at the capping station. Due to its cross-sectional shape, the .OMEGA.-shaped shell plate is difficult to convey and position. Further, the .OMEGA.-shaped shell plates are apt to fluctuate in size and shape, and accordingly, it is very difficult to cap the .OMEGA.-shaped shell plates with high accuracy. Further, since capping and clinching must be effected at a station different from the station at which the shell plate is bent, the apparatus is enlarged in size and complicated in structure.